A pharmaceutical company claimed that experiments showed that its drug could effectively reduce the growth of cancer cells by 35 percent. However, when five independent laboratories conducted the same experiment, they measured a reduction rate of only 5–8 percent. How did these laboratories show that the pharmaceutical company’s claims were invalid?

The labs used the pharmaceutical company’s inadequate data.
The labs produced false data.
The labs recorded data incorrectly.
The labs were unable to reproduce the pharmaceutical company’s data.